Immunohistochemical expression of beta-catenin in ampullary adenocarcinoma: a cross-sectional retrospective study

Ampullary carcinomas are uncommon malignant tumours of the digestive system, they usually are adenocarcinomas presenting histologically as three types: intestinal, pancreaticobiliary and mixed. β-catenin is a multifunctional protein involved in physiological homoeostasis and intracellular adhesion. Abnormal nuclear accumulation of β-catenin has been described in many malignancies such as colon, breast, liver and others. The relationships between the immunohistochemical expression of β-catenin and the subtype, the grade and the stage of ampullary carcinoma are studied. MATERIAL AND METHODS: A cross-sectional retrospective study was done on 25 formalin-fixed paraffin-embedded blocks of ampullary carcinoma: Cases were collected from the archives of the pathology department in the Gastroenterology and hepatology teaching hospital, medical city/ Baghdad from January 2019 to March 2022. The data of the patients and the characteristics of the tumour were derived from the pathological reports; additional sections from the block were stained with β-catenin immunohistochemically. RESULTS: 25 paraffin blocks from patients with ampullary carcinoma (12 males, 13 females) were included in the study. 64% of the cases are classified as pancreaticobiliary, 20% as mixed, 12% as intestinal and 4% as adenosquamous type. Eighty-four percent of the cases are moderately differentiated, and the remaining is poorly differentiated. Most cases show strong β-catenin membranous staining and 80% express 3+ staining of cytoplasmic β-catenin. Regarding nuclear β-catenin staining, 56% has negative staining. CONCLUSION: No significant association was found between the cytoplasmic and the nuclear expression of β-catenin and the tumour type, size and lymph node status. The grade of the tumour showed a significant correlation with the cytoplasmic expression; while, no correlation was noted with the nuclear expression. This study results do not support the use of beta-catenin as a diagnostic marker or prognostic marker in ampullary cancers.